Types of Foam Packaging

Posted on October 16, 2011 by

Foam is widely used as an inner cushioning material in packaging. Foam is a very versatile packaging material, and can be shaped into custom sizes easily using various methods.   Packaging foam can be divided into three main categories.  EPS, Polyethylene, and Polyurethane. Each has its unique benefits.  I will spend some time here to briefly review these.

Expanded Polystyrene or “EPS”, is  a white rigid closed-cell foam material. It is made by expanding polystyrene beads with steam and bonding the beads together under pressure to form blocks, sheets, 0r the common packaging “peanuts” that are used as a cushioning void fill.  EPS foam exhibits good insulation properties and for this reason it is in used coolers, wine shippers and bio-tech packaging.  It can also be molded into shapes if the volume is large enough to offset the cost of tooling.  It can be cut into an unlimited variety of shapes using hot wire cutting. EPS sheets are not the best choice for shock absorption because it is rigid, and can break if it’s subjected to a concentrated force. If you need something to absorb shock consider polyethylene or polyurethane material.

Polyethlene foam or more commonly known as “P.E.” foam is a strong resilient closed cell foam. It is renowned for its ability to withstand great amounts of pressure without losing its original cushioning properties. It is used for shock absorption, vibration dampening, and void fill.  It is typically found as planks or rolls. Polyethylene foam is typically used to secure sensitive products  by forming it into end caps. These are typically made  by cutting down a large plank and then die cutting it. End caps slide around each end of the product and holds it securely in place. Sheets can also be cut to specific sizes and used as liners inside a box.  P.E also comes in large rolls of thin material – typically about 1/8″ thick. This form of P.E. is typically used as void fill or slip sheets to protect products.

There are different color families of P.E foam and each represent the density (pounds per cubic foot) of the foam. Some of the colors available are: , Green, Light Blue, Pink anti-static, White, and Black.

Polyurethane foam, also known as urethane foam is a flexible, open-cell type of foam that has a many applications due to its resilience and durability. Urethane has a softer feel, especially in the lower density and firmness ranges. They are most often the foam of choice for smaller, lighter, and shock-sensitive products. Urethane starts out  as large blocks, which can be sawed down and die cut.  Urethane can also be convoluted to form an egg crate look. There are different grades of urethane foam and they are color coded.

The sales team at St. Pete Paper will gladly help you choose the right type of foam for your application. Feel free to give us a call at 727-572-9868  any time to discuss your packaging needs.

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Printing Methods for Corrugated Boxes

Posted on July 15, 2011 by

The process of transferring ink to the corrugated box has evolved through the years with newer technologies always replacing the older methods and equipment. Printing on corrugated was limited to relatively simple graphics for most of the 100 years of the existence of corrugated packaging.

Changes in the way goods are marketed in recent times have pressured corrugated box manufacturers to expand their print capabilities to enable the printing of more sophisticated images.  Point of purchase retailing has resulted in the need for corrugated packaging to expand its role from that of just being a shipping container to also act as a selling tool at the retail level.

The methods of printing on corrugated board can be defined in four categories. post print, pre print , litho lamination, and digital.

Post-print has been and remains the dominant technology for printing corrugated containers.  The term refers to the fact that the printing step occurs after the linerboard and medium have been combined to form corrugated board.  Great care must be taken in post-print not to crush the flute structure during printing.  Skill is required by the machine operator to regulate the pressure of the blank to the printing plate in order to achieve a quality printing job.  Letterpress, flexographic and silk screen are the process used in post print.

Preprint involves printing the linerboard before it is combined into corrugated board.  In this process a roll of linerboard is unwound and printed on a printing press and then is rewound into a roll to be made available to the corrugator.  This roll-to-roll printing process occurs in one pass through the printing press.  The advantage of preprint is that printing pressure is not an issue. The linerboard is passed around steel rolls, which act as a solid backup to the linerboard during printing.  This system takes the worry of too much pressure out of the printing equation and allows very sophisticated photographic quality printing to be achieved on corrugated. The only drawback is that for this method to be economical a large volume of boxes is needed.

Another method which has allowed more sophisticated images to be displayed on corrugated, employs the lithographic printing process.  The method involves printing a sheet of publication grade paper on an offset printing press and then laminating the printed sheet directly to the corrugated board, or a finished box.   Another way lithography is used is known as single face lamination. It involves laminating the printed sheet directly to the medium as the outside liner. Litho-lamination generally produces the most sophisticated form of printing for relatively small packages for the consumer market.

Digital printing is the newest method of printing on corrugated and is still in its infancy compared to other methods.  Digital printing basically uses inkjet printing technology, but adaptations allow it to print on a larger scale, print thicker substrates, and the inks are formulated for linerboard. Graphics from a digital computer file are transmitted directly to a printer that plots the graphics onto the corrugated board. The need for printing plates is eliminated, however because it is a time consuming process it is used primarily for short runs.

Here at St. Pete Paper we will be happy to go over these methods in greater detail and can help you determine the most practical method of printing for your application.

 

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Buying from your Local Box Manufacturer

Posted on March 4, 2011 by

Sometimes we receive quote requests to manufacture custom boxes from far away distances.  Although we would be happy to receive all orders within our capacity, it is not usually economical for a company to purchase from box manufacturers outside their local region due to the added freight costs.  This especially true the for short runs.  For example;  say a  business needs 300 custom sized boxes for their product.  They place an order from a manufacturer 400 miles away.. The freight for this may run upwards of $150  (depending on the size and weight)  which will add a minimum of  $.50 per box.
In contrast there is  likely a box manufacturer within 100 miles of the business who is just as capable of manufacturing the order and freight costs are much more reasonable.  Box manufacturers are located in just about every metropolitan area in the United States.  It is worth your time to do a search for box manufacturers locally.  An added benefit of using a local manufacturer is also having the opportunity to meet in person with a sales representative who can assist you in selecting the right box style and material for the product you need packaged.

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Bursting Test vs. ECT

Posted on February 17, 2011 by

Over recent years many of our customers have asked us the difference between the bursting test and edge crush test (ECT), and how it relates to their boxes.  Both tests are different and measure separate properties of the material; however they both deal with measures of durability and strength.  Within each test there are many grades.
When one of these tests is performed on a random sample,  the results allow the sheet manufacturer to assign a certain grade.  Usually the manufacturer will plan to run a certain grade and knows what combinations of liner and medium will meet the test requirement. It is important to point out that even if a run is designated to be a certain test grade – for example  ECT,  it could also be burst graded and vice-versa  This is proven in day to day operations because it is not typically possible to tell the difference between similar grades of ECT and burst test sheets with the naked eye because they look and feel similar.  The only way to verify they meet a certain grade would be to perform the test on a sample, and in many cases the results may show that the particular sample meets a burst grade as well an ECT grade, thus proving that all corrugated sheets can fit into both testing methods, and overlapping of grades is common.

The bursting test sometimes refered to as the “mullen test” sets requirements as to the weight per unit area of material.  A given burst test corrugated sheet must weigh a certain amount per 1000 sq. ft.  When the weight of the material is met a  grade is given with units of pounds per square inch (psi).   This pressure is directly related to a boxes ability to withstand external or internal forces and thus to contain and protect a product during shipment.  Burst grades are usually used to withstand rough handling where puncture and tear resistance is needed.

ECT is a measure of the edgewise compressive strength of corrugated board.   ECT is directly related to the stacking strength of a box . It is measured by compressing a small segment of board on edge between two rigid plates perpendicular to the direction of the flutes until a peak load is established. This is measured in units of pounds per lineal inch of load bearing edge (lb/in), and reported as an ECT value.  ECT grades are primarily used when boxes will be stacked over a period of time, and the product weights are known.  A calculation can be performed using these variables to choose an adequate grade.

When designing a packaging solution, the best designers begin with the end in mind. Every packaged product has its own unique set of problems to solve. These include physical characteristics of the product, the mode in which the package will be shipped or stored, and the functions the package will be asked to perform. Your corrugated salesman should be the first point of contact to assist you in choosing the correct grade of corrugated you should be using for your boxes.

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Welcome to St. Pete Paper’s Blog

Posted on February 14, 2011 by

This blog was created as a resource to anyone who has an interest in corrugated packaging.  Corrugated packing is not just that plain brown boxes – but also includes wide variety of other applications from protective inserts to high graphic displays.  Foam packaging will also receive attention since it plays a role as a cushioning material.   We will discuss topics and challenges that we have come across in our more than 25 years of business – in the hopes that it might answer questions you may have related to your packaging needs.

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